So, my question (and bug report?) is why was it never extended? I added several var_dump() and print statements into the code so that I could see what was being called... It seems that the XenForo_CodeEvent::fire() was never called for load_class_datawriter as it never showed up in my dumps.
Cezz could probably really use the datawriter class, as she needs to access at least the thread ID, but I got her on her way working and overwriting actionAddThread(). Bug? Freak Coding problem?